Advanced Outgassing under vacuum
This test is used in extension to ECSS-Q-70-02A (see “Standard Outgassing”) and in accordance to ECSS-Q-TM-70-52A (kinetic outgassing of materials for space).
This test, with high sensitivity, is used for a detailed investigation of the mass transport of materials (mass-loss due to sublimation, evaporation, outgassing as well as redeposition of evaporated particles) under thermal vacuum. Since a vacuum microbalance records mass changes on-line, this test is used in extension to the screening test ECSS-Q-70-02A (mass change by weighing in air before and after vacuum exposure).
Mass loss by sublimation, outgassing, evaporation and the mass gained by redeposition are measured by weighing (ESTEC-standard) in an apparatus built according to the ESTEC-design.
Smallest mass changes can be determined and accelerated tests can be carried out. By on-line mass spectroscopy the species of the outgassing or evaporated particles can be analysed. For surface conditioning a sputter-ion-gun can be used. For evaporation a Knudsen-cell is built in, recondensation on any susbtrates can be measured using the microbalance. Calibration of impingement rate is done using a quarz crystal microbalance. If necessary associated examinations (e.g. LO and Scanning-Electron Microscopy, IR-Spectroscopy, Auger-Spectroscopy) can be made.
On-line Measurement of:
Mass-loss as a function of time and temperature
Mass-gain as a function of substrate, time and temperature
Mass spectroscopy of outgassing and evaporating particles
|Temperature||Between -150 °C and + 800 °C, also thermal cycles|
|Vacuum||< 10-4 Pa|
|Specimens||Max. 30 g, various geometry|
|Temperature control||By irradiation exchange|
|Accuracy of weighing||Vacuum balance drift: <5*10-7 g/h
Quartz-crystal micro-balance: <10-8 g/cm2